Designing nuclear energy systems with non-proliferation in mind
As climate change drives the need for cleaner energy, nuclear power is gaining attention, even in countries that had not planned new reactors. Sweden, for example, is exploring small modular reactors (SMRs) for future deployment. At the same time, geopolitical concerns make non-proliferation a priority for any new nuclear technology.
Early design decisions are crucial to ensure new nuclear systems remain unattractive for weapons development.
Why proliferation resistance matters
Deploying SMRs introduces changes in the nuclear fuel cycle that may raise proliferation risks. In Sweden, these changes could include:
- Load-following reactors
- Cogeneration of district heating or hydrogen
- Dry storage of spent fuel
- New reactor sites near population centers or industrial areas
Researchers need to assess how these developments affect proliferation risks and what measures can reduce them. The International Atomic Energy Agency (IAEA) developed the INPRO methodology to evaluate proliferation resistance in nuclear energy systems.
Nuclear safeguards and non-proliferation
The Non-Proliferation Treaty (NPT) sets a global framework to prevent the spread of nuclear weapons, promote peaceful nuclear use, and encourage disarmament. Almost all countries, including Sweden, are parties to the NPT and must conclude a Safeguards Agreement with the IAEA.
Safeguards include:
- Nuclear material accountancy and control
- Seals and surveillance of materials and equipment
- Inventory checks and on-site inspections
These extrinsic measures ensure nuclear technology is used only for peaceful purposes. In addition, intrinsic design features—like inaccessible fuel, unsuitable material forms, or secure facility layouts—can make systems inherently less attractive for weapons use.
Early integration of proliferation-resistant design
The INPRO methodology helps plan nuclear systems with strong proliferation resistance. It considers both intrinsic features (reactor design, fuel, facility layout) and extrinsic measures (regulations, safeguards). Early coordination among designers, operators, regulators, and safeguards inspectors enables a Safeguards by Design (SbD) approach, embedding non-proliferation considerations into every stage of planning, construction, and operation.
Sweden’s nuclear energy landscape
Sweden has operated commercial nuclear reactors since the 1970s. Today, six of the original twelve reactors remain at Forsmark, Ringhals, and Oskarshamn sites. Recent government efforts aim to support new nuclear projects through improved licensing, financing models, and waste management planning.
In 2024, state-owned Vattenfall announced plans to explore SMRs at the Värö Peninsula near the Ringhals site, marking a major step toward Sweden’s first new reactors in decades.
Assessing SMRs for proliferation resistance
Using the INPRO methodology, researchers evaluated a hypothetical scenario of three light water SMRs at Forsmark, including a dry storage facility for spent fuel. The assessment focused on five key requirements:
- Adequate legal framework on non-proliferation
- Low attractiveness of nuclear technology and materials
- Effective integration of IAEA safeguards
- Multiple measures to deter misuse
- Officially approved design optimization for proliferation resistance
The study emphasized the first three requirements.
Extrinsic measures
Sweden already has strong legal and regulatory safeguards, an open fuel cycle with deep geological disposal at Forsmark, and multilateral ownership of nuclear assets. Existing safeguards procedures can be adapted for new SMRs. Additional recommendations include requesting an IAEA advisory mission to confirm resources for safeguarding new facilities.
Intrinsic features
The hypothetical SMRs use familiar light water technology, smaller reactor cores, baseload operation, and fresh fuel similar to current reactors. The technology’s attractiveness remains High, but safeguards and regulations mitigate risk.
Fresh fuel quantities for the SMRs would be moderate, and used fuel storage in water ponds and dry casks would not significantly increase proliferation risk initially. However, cumulative storage at a dry facility over decades could create a Very High attractiveness site, highlighting the importance of careful design and Safeguards by Design integration.
Conclusion
The assessment shows that new SMRs can be deployed in Sweden without significantly increasing proliferation risk. Key factors include:
- Strong existing safeguards
- Well-designed facility layouts
- Early collaboration between designers, operators, regulators, and inspectors
Ongoing research will explore additional intrinsic and extrinsic measures, including fuel handling, SMR operational modes, and long-term storage strategies, to further strengthen proliferation resistance.
By combining design foresight, regulation, and international oversight, Sweden can expand its nuclear energy system while maintaining strong non-proliferation standards.
